How many species are there?

Species estimates:

How many species are there in the world?

This is a very good question, but the truth is, its very hard to
know, or even estimate. Currently there are about 1.4 million species
described. Yet, we're probably far from being close to the actual
number of species.

Take this into consideration. In a famous study conducted in Panama,
19 trees were "fogged" with insecticide and the dead were
collected as they fell through the canopy. In this study, nearly
1,200 species of beetles alone were collected. Of those, 80 percent
were not known to science. While it may be dangerous to extrapolate
numbers like these to other places, it gives at least a high estimate
of the number of species that could exist on earth - that high estimate
being around 100 million species. A low estimate is 2 million. The
best estimate might be around 10 million. But even if that’s
the case, it means we've only known about a small fraction of what
is presently there.

Many of the species that we're discovering live in areas that are
not often studied. Take the sea floor for instance. Hydrothermal
vents along the floor provide a type of chemical energy for bacteria.
These bacteria use this energy like plants use the energy of the
sun. They then form the base of a giant food web thousands of feet
below the surface. Only until recently have we been able to discover
this new habitat. Now scientists believe there could be as many
as a million species just in on the ocean floor.